The Thin Blue Line
by Aggammenonn
Summary: The day after the events of Number One Fan, Castle is forced to make a choice. He must choose between accepting a newly created position or ceasing all field work with the team. For Castle, there is really no choice. Season 6 AU


Disclaimer: I do not own Castle

AN

Bit blocked on my other stories at the moment and I've watched a lot of Castle lately.

* * *

**Castle**: We should get a warrant, run his subscribers against any hate mail that the Vegas might have gotten.

**Montgomery**: You sure you got no cop in the Castle family tree?

**Castle**: No, us Castles are mostly con artists and circus folk, sir.

**Montgomery**: No, I think there's a little cop in there somewhere.

* * *

Castle stepped out of the elevator into the hallway connecting to the homicide bullpen with a spring in his step and the customary two coffee's in his hands. He paused to look around at the cops busy with their work with a fond smile on his face. When Beckett had worked in DC, he'd really missed coming here, somehow he'd internalized the cops here as extended family and he took great pride that the feeling was returned. Now that Beckett was reinstated, it truly was like coming home.

Making his way to his chair by Beckett's desk, he returned the respectful nods from the passing cops with a broad smile. Setting Beckett's coffee on her desk, he dropped into his chair and let his eyes soak in the sight of his partner as she sorted through the never-ending paperwork.

"Good morning detective," he said cheerfully. "Anything exciting happening today?"

Beckett rolled her eyes, though her fond smile betrayed her real reaction.

"We came to work together Castle, you spent all of five minutes getting the coffee. Were you really expecting something in that time frame?"

Castle shrugged and took a sip of his coffee.

"Well no, but you can't blame a man for asking," he said with a chuckle. "It just seems so wrong that you spend more of your time slaving away at your desk then you do chasing killers."

"That's the way the world works," Beckett said dryly. "Of course, you're more than welcome to finally do your share for a change Partner. You know, get some hands on experience with _real_ police work."

Castle pasted an over the top horrified expression on his face.

"Detective Beckett, is there no low you won't stoop to? I've happily walked through hell with you and would do so again but that," he pointed at the folders on her desk. "That is where I draw the line. I have enough paperwork of my own to do."

Rolling her eyes at Castles overly dramatic delivery, complete with theatrical shiver of horror, Beckett glanced around the bullpen and leaned forward.

"You know," she whispered huskily. "We could always work out a payment plan."She couldn't stop a small chuckle when Castle instantly jerked upright in his chair and locked his eyes on her.

"Really," he squeaked excitedly before visibly calming down. "I mean, I find your offer intriguing and I wish to know more."

Any response from Beckett was halted when Captain Gates opened her office door and stuck her head out.

"Mr. Castle. My office, now!"

Stiffening in shock, Castle met Beckett's questioning glance and shrugged.

"Rick, what did you do?" Beckett asked quietly.

"I have no idea," Castle replied uncertainly. "I didn't interact with her when you were in DC except for that case with the CIA and you know she called me yesterday about that one. I've tried really hard to make her not hate me anymore."

Beckett grabbed his hand and squeezed lightly in support.

"Well, go see what she wants but be on your best behavior Castle. Don't give her a reason to kick you out ok?"

"Do my best," Castle mumbled as he stood up, reluctantly letting go of Beckett's hand. Taking a deep calming breath, he took comfort from the supporting gaze of Beckett and the discrete thumb's up from Ryan and Esposito before making his way to the captain's office.

Knocking on the open door, he stuck his head into the office.

"You wanted to see me sir?"

Gates peered up at him through her reading glasses before nodding at the chairs in front of her desk.

"Have a seat Mr. Castle. I just need a moment to finish up here."

Castle crossed the office to the chair and sat down, doing his best not to fidget as he waited for Gates to finish up.

After letting him stew for several minutes, Gates placed the file she was reading on her desk with a sigh.

"Mr. Castle, why are you still here?"

"You told me to sit sir," he answered, taken aback by and misunderstanding the question.

Gates took off her reading glasses and fixed him with a stern glare.

"I don't mean here in my office Mr. Castle, I mean here in my precinct. I find it hard to believe you need more 'research' for your books and you've obviously succeeded in your pursuit of Detective Beckett, so I ask again. Why are you still here?"

Castle wilted under her gaze and held his hands up helplessly as he searched for an answer that wouldn't piss the stern woman off. After a few moments, he mentally shrugged and decided that he was best served by telling her the truth as best he could.

"Sir, obviously I enjoy working with Detective Beckett but I've also come to view the officers here as a second family of sorts. When I'm not here, I feel as if I'm letting my team, my family down but it's not just that. " He paused in frustration and ran a hand through his hair. "I love being a writer sir and without any false modesty, I'm damn good at it but the past five years here gave me a taste of true satisfaction. There is a thrill to matching wits intellectually with killers and a deep satisfaction in catching them and providing closure for the victim's families. Simply put, I feel like I belong here sir."

"I see," Gates said neutrally, a hint of a satisfied smile on her face. "It should come as no surprise to you that I've watched you closely since I took over the 12th. In my mind, police work should be left to the professionals and your presence here was extremely grating, especially after you went over my head and involved the mayor. I could have refused, even if it did cost me my career or any chance of advancement, but I was curious about why you were so desperate to return and why serious and focused detectives like Beckett, Ryan and Esposito were so adamant on your presence."

She held up her hand to forestall any response from Castle.

"No Mr. Castle," she said calmly. "I will allow you a chance to speak but for now, you will be quiet and listen for once. Yes, your team all came to me separately and begged me to allow you to return before I received the call from the mayor."

She unlocked her gaze from Castle and swiveled her chair to gaze out the window at the city in contemplation.

"I've looked over the records Mr. Castle and I found something very interesting. Under Captain Montgomery, the 12th had an 82 percent homicide case closure rate which is actually very impressive, especially for a town like New York. Then, five years ago, that case closure rate spiked to 94 percent. As it stands, this precinct now has the highest homicide case closure rate of any large metropolitan area in the entire United States."

She swiveled her chair back towards him with a stern expression.

"That Mr. Castle is why I allow you to remain despite our repeated disagreements. While I find your personality irritating and I'm not fond of your team's reliance on you, you do get results but others have noticed and it may cause some problems."

Castle cleared his throat and received a nod from Gates that he could speak.

"Sir, before we go any further here, I would like you to know that I _do_ respect you. I would be lying if I said I didn't miss Captain Montgomery, he was my friend, but despite our clashing personalities, I think you are every bit as much of a captain as he was. Now, what sort of problems have cropped up sir?"

Gates regarded Castle with a direct look as if scanning him for any hint of falsehood. Seemingly satisfied, she lowered her gaze to the folder she'd been reading when Castle entered her office.

"I admit that surprises me somewhat Mr. Castle though I do appreciate it." She tapped her finder on the file and changed the subject. "Are you familiar with the Auxiliary Police Mr. Castle?"

Castle shrugged, confused by the sudden change of subject.

"As much as any other New Yorker I suppose. They're the NYPD's unarmed version of volunteer firefighters. May I ask why you asked me that sir?"

Gates sighed in frustration and irritation.

"Because of the situations you've gotten yourself into and the results of those situations, your friend the mayor pushed through an ordinance in the city council. They've decided to create a new division of the Auxiliary Police to be known as the Auxiliary Detective Bureau."

Castle gulped at the glare Gates sent him as she finished speaking, he could almost physically feel the daggers her eyes were shooting at him.

"Captain Gates, I assure you that I had no knowledge of this. I can see that this upsets you but I'm unclear why. Certainly having more detectives, even if part-time and unarmed is a good thing?"

"That's just it Mr. Castle," Gates said caustically. "These new 'part-time detectives' will, unlike the rest of the Auxiliary Police, be armed and fully accredited as peace officers. The program in and of itself isn't a bad thing but this is New York Mr. Castle. These slots with undoubtedly go to those with the best connections, not those most worthy, unless we establish a precedent here."

Reaching into her desk drawer, Gates pulled out a gold badge but instead of a medallion like a regular detective's, this was the seven-pointed star of the Auxiliary Police. A thin smile crossed her face when Castle paled and his eyes widened in shock.

"Mr. Castle, you are the first person to be offered this opportunity but understand this, if you accept, things will be very different for you."

Castle met the captain's eyes evenly, though a bit nervously.

"What would change sir?"

"You would be required to attend the next academy class for starters," Gates replied. "Rules and regulations that you now ignore would apply to you. You would be required to attend mandatory trainings and meetings as well."

Castle's eyes darted towards the figure of Beckett at her desk.

"Sir, what about my relationship with Detective Beckett?" He asked with a dry mouth.

That thin amused smile returned to Gates face as she watched him squirm.

"As long as you continue to maintain a professional relationship at work, I'm prepared to overlook it," she finally said to let him off the hook. "I would certainly hate to breakup my most effective homicide team but make no mistake Mr. Castle, I will if I have to, understand?"

"Yes sir!" Castle exclaimed quickly. "Sir? If I chose to accept this offer, would I still be allowed to work with the team until I was required to attend the academy?"

Gates nodded solemnly. "Yes Mr. Castle. After you finish the required paperwork and qualify on a service weapon, you will be allowed to work with your team."

"Sir, what happens if I decline?"

Gates frowned at the writer.

"You would continue to be allowed to act as a consultant but you would be bared from field work with your team."

"Sir, that seems very unfair," Castle protested.

"Mr. Castle," Gates said sharply. "Time and again you have entered situations that a civilian should not. While it can be argued that it shows your determination as a consultant, I will not stand by and continue to allow it. If you truly wish to be Detective Beckett's partner as you claim to be, you will do so as a sworn peace officer."

"Yes sir, I understand," Castle said quietly when Gates finished. "Stated like that, it would be hard to fault your logic, though I wish I could." He sighed and gazed out the office window at Detective Beckett with affection.

Shaking his head, he turned back to Gates and stared at the badge on her desk with mixed longing and loathing.

"Captain Gates," he said softly. He raised his eyes and met hers with determination. "Tell me, do you think this is a good idea?"

"It hardly matters what I think," she scoffed. "I've been ordered to offer this to you and I have."

"Humor me please sir," Castle said with a thin smile. "Do you believe I should do this?"

Gates let out a large sigh and massaged the bridge of her nose to buy time to think.

"Mr Castle," she finally replied. "I hesitate to say this because of your ego but yes, I do think that you should accept. I've personally seen the dedication you have to your team and how serious you can be when it matters most. If you bring that seriousness and focus to the job and set the precedent for all other Auxiliary Detectives to follow, then again yes, you should accept."

She fixed him with a stern glare, hellfire blazing in her eyes.

"If however you do not take it seriously, then no you should not."

Castle nodded and blew out a breath as he considered his options. He froze a moment as he realized that there were other people he needed to consult.

"Captain Gates, such a life altering decision should not be made in a vacuum. May I have some time to discuss this with my fiancée?"

That thin smile returned to her face, and Castle though he saw a hint of approval in her eyes.

"I was wondering if you would remember to do so," she admitted. She glanced at the clock on the wall behind him. "I need to leave for a meeting in twenty minutes Mr. Castle, I expect an answer before I leave."

"Yes sir," Castle said, standing from his chair and hurrying towards the door. Hitting the bullpen, he rounded up Ryan and Esposito with his eyes and made a bee-line for Beckett.

"Kate, we need to talk," he said in a near whisper. "Privately with the guys."

Beckett looked up startled and froze a moment at how serious her normally upbeat partner looked.

"Alight," she said, getting up from her seat. "We can use one of the conference rooms."

The team followed Beckett into an unoccupied conference room, Ryan and Espo branching off to close the blinds. Turning to face Castle, Beckett planted her hands on her hips.

"So, what happened in Gates' office Castle," she said. "You seem a bit spooked."

At the prompt, Castle started out of his funk and he rapidly explained the new position and offer. He took care to point out both the upsides and the downsides though Ryan and Esposito seemed more amused than anything else.

"You serious bro?" The Hispanic detective said, holding back laughter. "Seems like you'd get some real research on what it's like to be a cop." He paused as a wide grin spread across his face. "You know Castle, maybe Beckett would even let you drive if you joined up."

"Ha ha," Castle said irritably. "Very funny Espo. I'm on a time-limit here guys, would it bother you if I accept this?"

Esposito and Ryan made eye contact with each other and Espo deferred to his junior partner with a shrug.

"Castle," Ryan said slowly. "We pretty much already consider you to be one of us. I don't think this would change that, unless you decline of course. If you do, we will dump some of the paperwork load on you since you won't be in the field with us."

"Ah," Castle said dryly. "I find that to be an excellent argument in favor of accepting, thanks guys."

"Any time bro," Espo replied wryly. Grabbing Ryan's arm, he began dragging his partner from the room. "And now, I think we'll go and let you two talk."

"Ah, I don't want to Javi," Ryan whined as he was dragged from the room.

"Quiet," Esposito whispered at his partner as he closed the door behind him. "Do you really want to get caught between mom and dad again?"

Ryan stiffened and let the childish image drop with a shudder.

"No, I don't think I do," he admitted as he headed back to his desk. "I'm still kinda curious what Beckett's gonna say though."

"We'll find out soon enough," Espo said with a shrug. "If Beckett doesn't like this idea, I don't see Castle accepting."

"I don't know, he can be kinda stubborn," Ryan countered.

"True, but he knows how much this job means to Beckett and this is one of the few things I could see him backing down on without a fight for her."

"I suppose," Ryan said as he ignored his paperwork to watch the door to the conference room with undisguised curiosity. "Be kinda cool for Castle to actually be a cop though."

"Maybe," Esposito replied, his eyes also glued to the door. "I'm a bit irritated he gets to skip right to detective though. Being a uniform builds character."

"Sure but he won't be getting paid for his work and he's also more or less trained with us for the past few years," Ryan said with a snort of amusement. "So, what would we introduce him as. Detective Castle or Auxiliary Detective Castle. Ohh and what about when they get married, would it be the 'Detective Castles'?"

"Bro, I worry about you sometimes," Esposito said, shooting his partner a withering look. "Besides, he'd be _her _partner so it's not like it really matters to us."

"Not always Javi," Ryan retorted. "Sometimes he comes with us."

Esposito shuddered at the reminder.

"Not gonna forget Atlantic City anytime soon, that's for sure," he muttered under his breath to the amusement of his partner.

* * *

As soon as Ryan and Esposito cleared the room, Castle laced his fingers with Beckett's and pulled her into a deep, fiery kiss. Before the two could lose themselves, Castle gently pushed her away regretfully.

"Sorry Kate, I know we aren't suppose to do that here but I really needed that."

Regret, amusement, love and an undercurrent of restrained lust shined in her eyes as she gave him a sly little smile.

"I suppose I can let you get away with it this time Castle, but I will find a way to make you pay. I'm the tease in this relationship buster."

"And you do it so well," Castle agreed genially. "So, what do you think?"

"I don't know Castle," Beckett replied softly. "I don't want you to do this just for me, so I guess my question is if this is what you want."

"I'm not sure I have a choice Kate," Castle said seriously. "If I don't accept the offer, I'm restricted to helping out here at the precinct and I don't think I could handle that." He began to pace as the words continued to flow from him unfiltered.

"We both know how dangerous this job can be and only the fact that we go in and face these things together allows me to deal with it. But I accept it because this is also who you are Kate. You can no more stop being a cop, then I could stop being a writer. If I accept this offer, I will finally be your partner in the eyes of the NYPD."

"And if I told you that I didn't want you to accept the position?" Kate asked with a raised eye-brow.

Castle's shoulders slumped in resignation.

"Then I would accept your decision because this is your half of our world. I wouldn't like it but I would do my best to support you from here in the station." He gave her a wry smile. "I don't promise I won't whine about it though."

Beckett rolled her eyes and set her hands on her hips.

"I promise I'm a big girl and can take care of my self Castle," she said with a hint of exasperation. "So do you actually want to do this, or do you just not want to let me out of your sight." The little smirk she couldn't help robbed the words of any potential sting.

"Mmm, there is certainly something to that theory," Castle replied huskily before becoming more serious. "I think that I do want to do this Kate, assuming that you're willing to accept it."

Beckett stepped forward and wrapped her arms around her fiancé tightly. She slid her right hand up he back and tousled his hair at the same time she leaned forward to whisper in his ear.

"I have some questions for Captain Gates but assuming you aren't being set up to fail, I would be delighted for you to formally become my partner."

Castle breathed a sigh of relief and gently stroked his hand down Beckett's spine. Leaning down he placed a quick kiss on her lips before resting his forehead against hers.

"Thank you Kate," he said softly. "I know that couldn't have been easy for you."

"Easier than you'd think," Beckett said pulling her head back and giving him a bright smile. "I'm looking forward to you _finally_ doing your share of the paperwork."

"Bah," he pouted. "There is no way it's as bad as you guys keep saying," he said, causing Beckett to laugh delightedly.

"Oh, you'd be surprised," she said with a mischievous twinkle to her eyes. "Now, time for me to go talk to the captain."

Reluctantly pulling out of her embrace with Castle, Beckett briskly strode out into the bullpen pausing on her way to the captain's office long enough to shoot a glare at Ryan and Esposito as the two hurriedly pretended to be busy.

Rolling her eyes at the antics of her boys, Beckett knocked on the open door of Gates' office.

"Sir, may I have a few minutes of your time?"

Gates looked up from her paperwork and seemed unsurprised to see Beckett.

"Come in Detective Beckett. I've been expecting you."

Nodding, Beckett closed the door and crossed the office to the chairs in front of Gates' desk. Getting a nod of permission, she sat down and regarded her boss calmly.

"Sir, how political is this offer for Castle? For that matter, what is the driving force behind creating auxiliary detectives anyway?"

Gates watched Beckett calmly for a few moments before she began to speak.

"This is very politically driven Detective Beckett, but some of it also stems from actions taken by Mr. Castle himself." She paused to gather her thoughts. "Yesterday, he willingly offered himself in trade as a hostage for a little girl and her mother. This isn't the first time he's done something like that, and it most certainly won't be the last." She held up a hand to forestall a response from Beckett.

"Yes, I am well aware that there are extenuating circumstances but such dangerous events are no place for a civilian, even a civilian consultant. I know this, the mayor knows this, even the city council knows this. I think deep down that you Detective Beckett know this as well."

"I can see the point," Beckett admitted grudgingly. "Still, Castle isn't exactly your normal consultant."

"Of course not," Gates said with a chuckle that startled Beckett. "They certainly broke the mold with Mr. Castle and I for one and profoundly grateful for it. As much as he and I clash, I do understand why your team has faith in him detective."

"Sir, I think we're getting a bit off subject. Can you tell me why Castle other than his tendency to attract trouble?"

"Well, there is the P.R. Angle. Millionaire mystery writer joins NYPD. Certainly a good thing in the view of those at 1PP. Additionally, I want Mr. Castle to set a standard for those joining the ranks as auxiliary detectives. I don't want to see this program used for kickbacks to those with connections, even if Castle originally got in that way. I know the man well enough to know that he will do his absolute best to make you and your team proud, and I think that's exactly what this program needs as a precedent."

"I see," Kate said quietly as she digested the information. "Sir, I'm sorry. I thought maybe you were planning on having him fail so you could get rid of him."

"Given my relationship with Mr. Castle, I could see why that might concern you," Gates said evenly. "But as I told him and you just now, I _want_ him to do his best for this program. I want him to set the bar so high that no one will even consider using these slots for political connections. And given everything your team has encountered with him, I think it's time for Mr. Castle to stop 'playing cop' and to actually join the family."

"So it's something of a shotgun wedding sir?" Beckett asked in an amused tone.

"If that's what it takes," Gates confirmed. "I'm also looking forward to his face when he discovers the joy of paperwork but you don't have to tell him that."

"Yes sir," Beckett said with a smirk as she stood up from her chair. "Should I send Castle in for you on my way out sir?"

"No need," Gated replied. "Just tell him to get in here and take your seat detective. I think we both know what his answer will be and I'm assigning you to haul him down to Human Resources and for his quals."

Beckett winced at the thought of Castle's likely reaction to the mountain of paperwork waiting for him downstairs. He was not going to like that at all though hitting the firing range for qualifications would cheer him up some. At least she didn't have to worry about that, though it was a minor source of irritation for her that Castle was a better range marksmen than she was. It was balanced out that she was a better shot in the field, and he so wasn't the one that shot down that damn drone no matter what he said, but on the range, he usually smoked her. Castle being Castle, he wasn't very modest about it either.

Opening the door and sticking her head out, she caught Castle's eye and jerked her head towards the office to summon him. She couldn't help smiling as he made his way over, he so looked like a like boy being called into the principals office, which was sort of true now that she thought about it.

"It seems that Captain Gates is expecting you to set the bar high for this program," she said quietly as he drew near. "Also, she seems near giddy at the thought of you subject to NYPD regulations."

"Shiny," Castle said back equally quietly. "That's a scary thought."

Making his way into the office following behind Beckett, Castle sat down across from the Captain near simultaneously with Beckett. Now that they were living together, things like that were becoming very common for them. People accused them of doing it on purpose but they were just so in-sync that it happened naturally. Judging from the expression of Gates' face, she was one of the skeptics.

"Have you come to a decision Mr. Castle?"

Castle took a deep breath and shot a loving glance at Beckett from the corner of his eye.

"Yes sir, I accept the offer."

"Very good," Gates said with a tight-lipped smile as she handed the gold Auxiliary Detective badge to him. "Detective Beckett will show you where you need to go for orientation paperwork as well as firearm qualifications and requisition." She held her hand out across the desk which Castle firmly shook.

"Let me be the first to say, welcome to the thin blue line Detective Castle."

* * *

**Castle**: Style section. Anything I need to know?

**Alexis**: The '70s are back.

**Castle**: Hmm. They're like the _Highlander_, they just won't die.

* * *

AN

Ok, this is more or less an experiment in a different writing style and as a way to unblock myself for my other projects. I hope you guys enjoyed it but updates will probably be sporadic.

The NeW York Auxiliary Police are real and kinda interesting to read about. They are unarmed uniformed officers that donate over a million hours of service to the city of New York every year. Kinda interesting to read about though I obviously took some liberties with it above.o7


End file.
